An in-mold injection molding method is being widely used to manufacture a front panel of a washing machine, an air-conditioner or the like, or an LCD window of a computer, a mobile phone or the like. In the in-mold injection molding method, a transfer film is installed between a fixed mold and a moving mold of an injection mold, and then melted resin is injected therein so that a pattern printed on the transfer film is transferred to an injection molding product at the same time of injection molding. Therefore, by using the in-mold injection molding method, injecting and transferring processes including injection, vacuum deposition, adhesion and the like can be reduced into one process, and thus manufacturing cost and defect rate can be considerably reduced.
In the in-mold injection molding method, the transfer film has a great influence on the quality of injection molding products. The transfer film generally includes a base film having releasing property, a protective layer which is stacked on the base film, a printing layer which is stacked on the protective layer and on which a predetermined pattern is printed, a deposition layer which is stacked on the printing layer, and an adhesive layer which is stacked on the deposition layer. After the injection molding process, the protective layer, the printing layer and the deposition layer are transferred to the injection molding product by the adhesive layer, and then the base film is separated and removed. Only a part of the protective layer which covers the printing layer is adhered on the injection molding product, and the rest parts thereof are removed with the base film.
In a conventional transfer film, a metallic material such as aluminum, copper, gold, silver, chrominum and titanium is deposited on the printing layer through vacuum deposition, sputtering deposition, electron beam vapor deposition and the like, thereby forming the deposition layer on the printing layer. Therefore, it is possible to embody inherent texture and color of each metallic material and thus to provide various metal colors to the transfer film.
However, in deposition layer of the conventional transfer film, if the metallic material such aluminum is deposited on the printing layer, metal particles forming the deposition layer are connected with each other without any gaps. As a result, a surface of the deposition layer has conductivity and also even radio waves cannot pass therethrough. This exerts an influence on reception and static transmission of signals, and thus it may cause damage to electronic components